Abstract:
This article discusses key mechanisms involved in removing
1 mg/L Mn from synthetic wastewaters in constructed wetlands
comprising water hyacinth (Eichhornia crassipes (Mart.) Solms) grown
under different nutrient levels of 1-fold (28 mg/L and 7.7 mg/L of total
nitrogen and total phosphorus, respectively), 2-fold, 1/4-fold, and 1/8-fold.
A mass balance was carried out to evaluate the key removal mechanisms.
Phytoremediation mainly due to phytoextraction substantially contributed to
manganese removal. However, chemical precipitation was absent, suggesting
that manganese has a higher solubility in the given average pH (6.2 to
7.1) conditions in constructed wetlands. Bacterial mediated immobilization
mechanisms also did not contribute to manganese removal. Sediments
constituted a minor sink to manganese, implying that manganese has a poor
adsorption potential. Constructed wetlands comprising water hyacinth are
effective at removing manganese from wastewaters despite the fact that the
plants are grown under higher or lower nutrient conditions. Water Environ.
Res., 81, 165 (2009).
